Liquid chromatographic analyzers are used for analyzing liquid specimens. A liquid chromatographic analyzer uses a needle to collect liquid specimens, which are injected into an analysis flowpath. When doing this, the liquid specimen is contained in a test tube (container) that is made of transparent glass or plastic.
Liquid chromatographic analyzers are sometimes used to analyze many liquid specimens. This has led to liquid chromatographic analyzers that are equipped with auto-samplers (e.g., see Patent Literature 1). FIG. 5 shows a perspective view of a portion of a liquid chromatographic analyzer. FIG. 6 shows a perspective view of a portion of an auto-sampler. FIG. 7 shows a perspective view of a rack on which two micro-plates are placed.
The auto-sampler 101 includes: a control unit 160 and housing unit 170, which houses rack 120, both of which are disposed in the liquid chromatographic analyzer main unit 150; a plurality of types (e.g., 7 types) of micro-plates 10 for holding a plurality of test tubes; and a plurality of types (e.g., 7 types) of racks 120 on which micro-plates 10 are placed.
A first micro-plate 10 is a case made of plastic. The first micro-plate 10 has a substantially rectangular parallelepiped shape with, for example, a width (X) of 85 mm, length (Y) of 125 mm and height (Z) of 25 mm. A first hole 11 through a 45th hole 11 are formed on the upper surface with five holes arranged in the X-direction (row direction) and nine holes arranged in the Y-direction (column direction). Each hole 11 is cylindrically-shaped which allows the lower half of a test tube to be inserted into a hole 11. The result is that 45 test tubes are held in the first micro-plate 10 arranged as described in the X-direction and the Y-direction.
Furthermore, a second micro-plate (not illustrated) is a case made of plastic. The second micro-plate has a substantially rectangular parallelepiped shape with, for example, a width (X) of 85 mm, length (Y) of 125 mm and height (Z) of 25 mm. A first hole through a 32nd hole are formed on the upper surface with four holes arranged in the X-direction (row direction) and eight holes arranged in the Y-direction (column direction). Each hole is cylindrically-shaped which allows the lower half of a test tube to be inserted into a hole. The result is that 32 test tubes are held in the second micro-plate arranged as described in the X-direction and the Y-direction. In other words, different types of micro-plates are available, featuring different number of holes and different hole locations. The description of the third through the seventh micro-plate is omitted here.
The first rack 120 includes: a bottom piece 121 having, for example, a width (X) of 94 mm, length (Y) of 260 mm and height (Z) of 20 mm; a recognition unit 122 that is disposed at the front end (positive Y-direction end) of the bottom piece 121; and a grip part 123 that is formed at the rear end (negative Y-direction end) of the bottom piece 121. Two of the first micro-plates 10 can be placed in the Y-direction (column direction) on the upper surface of the bottom piece 121.
The first rack 120 is provided with a recognition unit 122 which allows the control unit 160 of the liquid chromatographic analyzer main unit 150 to automatically recognize the type of micro-plate 10 that is housed in the housing unit 170. The recognition unit 122 includes: an enclosure 124 that is made of resin and having a rectangular parallelepiped shape; and a first light-shielding plate 125 that is made of resin and protruding 4 mm out in the Y-direction from the enclosure 124.
The second rack (not illustrated) includes: a bottom piece having, for example, a width (X) of 94 mm, length (Y) of 260 mm and height (Z) of 20 mm; a recognition unit that is disposed at the front end (positive Y-direction end) of the bottom piece; and a grip part that is formed at the rear end (negative Y-direction end) of the bottom piece. Two of the second micro-plates can be placed in the Y-direction (column direction) on the upper surface of the bottom piece. A recognition unit includes: an enclosure that is made of resin and having a rectangular parallelepiped shape; and a first light-shielding plate and a second light-shielding plate both made of resin and protruding 4 mm out in the Y-direction and being aligned in the X-direction. In other words, the first rack 120 and the second rack have different number of light-shielding plates 125, and each micro-plate 10 has its own dedicated rack.
The housing unit 170 is provided with a plurality (e.g., three) of photosensors 71 at positions corresponding to the recognition unit 122 of the rack 120. Beach photosensor 71 includes: an emission unit 71a that emits light in the Z-direction; and a detection unit 71b which detects light from the emission unit 71a with a predetermined distance (e.g., 20 mm) of separation between them. Furthermore, a first photosensor 71, a second photosensor 71 and a third photosensor 71 are formed to be aligned with each other in the X-direction. In this way, if three photosensors 71 are provided, there are eight possible combinations in which photosensors 71 may be shielded or not shielded from light. Since it is desirable for the housing unit 170 to be able to automatically recognize the absence of rack 120, it is possible for the housing unit 170 to discriminate among 7 types of micro-plates 10, excluding the situation where none of the photosensors 71 is shielded from light.
The control unit 160 determines the type of micro-plate 10 that is housed in the housing unit 170 based on the status of the recognition information (light-shielding information) that is detected by the three photosensors 71.
For example, if the first rack 120 is housed in the housing unit 170, since the first rack 120 has the first light-shielding plate 125, the first photosensor 71 is shielded from light while the second photosensor 71 and the third photosensor 71 are not shielded from light. From this combination, it is determined that a first micro-plate 10 is housed in the housing unit 170. If a second rack is housed in the housing unit 170, since the second rack has both the first light-shielding plate and the second light-shielding plate, the first photosensor 71 and the second photosensor 71 are shielded from light while the third photosensor 71 is not shielded from light. From this combination, it is determined that a second micro-plate is housed in the housing unit 170.